1. Field of the Invention
The invention relates to methods and apparatus for implementing computer supported telephony applications. More particularly, the invention relates to a control interface for facilitating the implementation of CSTA protocols.
2. Brief Description of the Prior Art
It is well known in the art to couple a computer to a PBX switch in order to provide enhanced telephony services. Such services include voice mail, fax on demand, text to speech email retrieval, call forwarding, interactive voice response systems, etc. Most of these applications are built around the CSTA standard which is a standard for the protocols used across the link between a computer and a PBX switch. The CSTA standard protocols utilize ASN.1, Abstract Syntax Notation number One, an international standard for specifying data used in communication protocols. Although ASN.1 is powerful, it is a complex language. The CSTA standard has been implemented in various proprietary PBX-Computer interfaces such as the “Call Bridge for Work Groups” which is the interface used in the Siemens Hicom 300 PBX.
Although the CSTA has made the development of telephony application somewhat uniform, the protocols provided by the CSTA are relatively low level. Even with the “Call Bridge for Work Groups” interface, a telephony application must take responsibility for many low level functions of the interface. For example, even using the “Call Bridge for Work Groups” interface, an application must take responsibility for creating, maintaining, and tearing down a TCP/IP socket connections; building and parsing the ASN.1 encoded CSTA stream; handling the reception system status heartbeat messages; sending and handling the result of System Status heartbeat messages; and managing the generation and timing of invoke Ids. In addition, many applications would also want to add diagnostic user interface features to indicate status, statistics and errors as they pertain to a particular connection. All of these functions must be implemented by the application. Many of these, such as the ASN.1 builder/parser are time-consuming and/or costly to develop/purchase.
It is known in the art to provide a higher level interface to some of the “Call Bridge for Work Groups”—CSTA interface. An earlier Siemens product provided limited ActiveX support for the following CSTA Services: Monitor Start, Monitor Stop, Divert Call, System Status Filter; and the following CSTA Events: connected, conferenced, connection cleared, delivered, diverted, established, held, agent logged off, agent logged on, network reached, agent not ready, queued, agent ready, retrieved, service initiated, transferred, agent work not ready, agent work ready, call info, system status, and universal failure error. However, there have not been any full high level interfaces addressing all of the features and events of the “Call Bridge for Work Groups”—CSTA interface. Moreover, there have not been any high level interface which aid in creation of common paradigms used in telephony applications. Furthermore, there have not been any high level interfaces which aid in the provision of diagnostic functions in telephony applications.